Hot-stamping molding for ultra-high-strength steel have some similarities with traditional cold-stamping molding in the aspects of molding process and die design. But due to the effect of temperature variation of blank, hot-stamping have some differences in ultra-high-strength products design, material selection and forming process design. Some special forming defects, such as local thinning, cracking and wrinkling, could appear in hot-stamping process due to these differences. In order to obtain uniform phase structure and get high-quality products, it is very important to be able to predict and control the blank temperature and the consistence of blank cooling rate. The thermo-mechanical characteristics of hot-stamping are studied with the material of ADVANCE1500 (22SiMnTiB). Based on the results of simulations and experiments, conclusion are drawn that the complexity of the product and the blank which contacts with die asynchronously causes the uneven distribution of the blank temperature. This is the key factor that leads to the poor mobility of the blank material and local thinning, cracking, wrinkling and other defects in forming process. Proper clearance between punch and die can reduce the probability of defects which could contribute to the improvement of hot-stamping process.